So I've got most of my library added to Calibre, but the tags are becoming unwieldy.

I have over 13k tags...is there anyway to parse this down or simplify them? Is there a way to automate it, assuming it isn't already? I just don't want to have to go in and manually do it for every book.

So I've got most of my library added to Calibre, but the tags are becoming unwieldy.

I have over 13k tags...is there anyway to parse this down or simplify them? Is there a way to automate it, assuming it isn't already? I just don't want to have to go in and manually do it for every book.

You can rename tags, which will merge them. So if you currently have 200 "Fantasy" and 100 "Fiction/Fantasy" books and you rename "Fiction/Fantasy" to simply "Fantasy", then you'll now have 300 "Fantasy" books (or fewer, if some books were tagged with both).

So:
1. Figure out a set of tags that you want to use. I have a pretty minimal set (Fiction, Nonfiction, Cooking, Computing, Biography/Autobiography, Art, History, Craft, Writing, Drama, Mythology, Manual, Journal/Paper, Short Stories, Poetry, Mystery, Thriller, Fantasy, Science Fiction, Romance, Alternate History, Young Adult, Children, maybe a few more) because I find that more useful than super-specific tags as far as searching goes. If you have, say, a huge collection of Science Fiction then maybe you want to split that into a few more categories (Cyberpunk, Space Opera, etc) depending on what your needs are, or maybe you need History - American, History - European, etc. Think about it and decide how you want to structure things.
2. Using the tag browser on the left, start renaming tags (if you've settled on "Mystery", then you can start renaming "Fiction - Mystery", "Detective", etc all into Mystery).
3. Tags that you don't find useful you can just delete in the tag browser (without having to remove them from individual books). So just hit Del on garbage tags and it'll get rid of it from all books.

The other thing you can do is bulk-edit, so you could (for instance) select all your Robert Heinlein and Isaac Asimov books, do a search/replace on ".*" in tags and replace with "Fiction, Science Fiction", and then select all the short story collections and add "Short Stories" to them. Then go correct whatever handful of their books that's wrong for. This will wipe out all the bogus tags that were on all those books. This is especially handy for authors that work almost entirely in one genre and for magazines/journals; you can cut through wide swaths of books quickly.

Hopefully that gets you a jump on the problem. Then you just need remember to edit the tags on new books as you add them.

1. Figure out a set of tags that you want to use. I have a pretty minimal set (Fiction, Nonfiction, Cooking, Computing, Biography/Autobiography, Art, History, Craft, Writing, Drama, Mythology, Manual, Journal/Paper, Short Stories, Poetry, Mystery, Thriller, Fantasy, Science Fiction, Romance, Alternate History, Young Adult, Children, maybe a few more) because I find that more useful than super-specific tags as far as searching goes. If you have, say, a huge collection of Science Fiction then maybe you want to split that into a few more categories (Cyberpunk, Space Opera, etc) depending on what your needs are, or maybe you need History - American, History - European, etc. Think about it and decide how you want to structure things.

One variation of this is to use hierarchical tags. So using the examples above, you might have Science Fiction.Cyberpunk, Science Fiction.Space Opera, History.American, History.European, etc.

You could then use the tag browser to find all Cyberpunk books, but you could also use it to find all Science Fiction books, without needing a separate Science Fiction tag. The tag browser can filter at any level of the hierarchy. Categorizing like this would also help reduce the time searching the tag browser even if you keep most of your existing tags.

Another suggestion when normalizing your tags is to create a dummy book and give it all the tags you want to keep. It's most useful when adding tags to new books, but it can also be used as a reference when renaming and deleting tags. After you're done you could delete the book, or keep it around for future reference.

A couple of years ago, I did almost exactly what sjfan suggests, and it worked beautifully--but it took weeks, what with a few thousand mostly mystery and scifi books at that time. The main reason was I did not think it through first, as he suggests, so I had a lot of back and forth. I ended up with about 300 tags, which has not changed since. A lot of these are place names, so I can find mystery stories set in Italy, for example.

I tried the hierarchical route first, but that nearly drove me crazy. I find it best, for me, to have very simple tags, mostly one word, or two at most, so I have "Hard" as a tag rather than "Hard Science Fiction". The reason is, you can concatenate the simple tags with searches or virtual libraries in any arbitrary way, without having to set it up beforehand. You can find complex combinations you would never think of until you want them. Mystery stories that are also scifi, in the future, but not murder mysteries? No problem.

Another suggestion, install the Quality Check plug-in and when you're done, look for excessive tags. After renaming and some editing, I still found books with like 20 tags, many of then just plain wrong. Publishers will put any old tag on a book, I guess hoping to get a hit in someone's search no matter what. One I remember is one of Doc E.E. Smith's Lensman books as "Contemporary Romance"--Really?

Publishers will put any old tag on a book, I guess hoping to get a hit in someone's search no matter what. One I remember is one of Doc E.E. Smith's Lensman books as "Contemporary Romance"--Really?

My personal favorite is when the books are tagged "book" or "ebook". I'm sure if I thought really hard about it, I could probably come up with a more useless tag than these, but nothing comes to mind at the moment.

That's why I consider this one of the most important rules of ebook management: Never trust someone else's metadata.

It's okay to download metadata, but always review it manually before calling it good. I try to clean up the metadata in batches as I add books to my library instead of waiting until I have 13k tags that need consolidating.

In my personal library (books I've read or my TBR), I do the tags manually. For the general library, which has all the ebooks anybody in my family has, I did what Sjfan suggested. With 13,000, yeah, it's going to take you a couple of weeks. Just pop in some nice music you haven't listened to for awhile, set a timer for an hour and adjust. After about an hour, you start making mistakes, so just take your time. Since I add books as soon as I download now, I immediately adjust the tags or the problem escalates again.

My personal favorite is when the books are tagged "book" or "ebook". I'm sure if I thought really hard about it, I could probably come up with a more useless tag than these, but nothing comes to mind at the moment.

Just after as I hit "Submit Reply" on the previous post I realized I might have to eat those words later if someone pointed out an actual use for those tags.

I still maintain that they have no business in a source of books or metadata. In your own personal library, sure. But if I download an ebook I've purchased, I can see no purpose for the "book" tag to be embedded in it already. Likewise if I download online metadata for a book in my library.

Marvin Reader (iOS) doesn't support custom columns so I have to use 'ebook' and 'fanfic' in the Tags if I want automatic collections/grouping. Kinda didn't make sense to create a custom column just for my paperbooks.

I find it best, for me, to have very simple tags, mostly one word, or two at most, so I have "Hard" as a tag rather than "Hard Science Fiction". The reason is, you can concatenate the simple tags with searches or virtual libraries in any arbitrary way, without having to set it up beforehand. You can find complex combinations you would never think of until you want them. Mystery stories that are also scifi, in the future, but not murder mysteries? No problem.

This is very much how I deal with tags. Almost all my tags are single words. For example, one book might be tagged: Romance, Fiction, Historical, Regency, England, Unread, Duke and another might be: Mystery, Fiction, Read, Science Fiction, Space, Read in 2018, Aliens, First Contact

I kind of feel like it gives me a lot of options when I search by tags. I might be wrong, but it seems like it really lets me drill down to specifics and get smaller groups of books back when I do search.

I manually tag every book (either individually or with bulk edit) and have tags turned off in the metadata download options. I just don't want anyone else's tags there. They aren't that helpful to me most of the time.